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Multiple constraints affect rice yields in West Africa. Among these constraints are viral, bacterial, and fungal pathogens. We aimed to describe the spatiotemporal patterns of occurrence and incidence of multiple rice diseases in farmers’ fields in contrasting rice growing systems in the western Burkina Faso. For this purpose, we selected a set of three pairs of sites, each comprising an irrigated area and a neighboring rainfed lowland, and studied them over four consecutive years. We first performed interviews with the rice farmers to better characterize the management practices at the different sites. This study revealed that the transplanting of rice and the possibility of growing rice twice a year are restricted to irrigated areas, while other practices, such as the use of registered rice cultivars, fertilization, and pesticides, are not specific but differ between the two rice growing systems. Then, we performed symptom observations at these study sites to monitor the following four diseases: yellow mottle disease, Bacterial Leaf Streak (BLS), rice leaf blast, and brown spot. The infection rates were found to be higher in irrigated areas than in rainfed lowlands, both when analyzing all observed symptoms together (any of the four diseases) and when specifically considering each of the two diseases: BLS and rice leaf blast. Brown spot was particularly prevalent in all six study sites, while yellow mottle disease was particularly structured geographically. Various diseases were frequently found together in the same field (co-occurrence) or even on the same plant (coinfection), especially in irrigated areas.

International audience; For many smallholder farmers in East and Southeast Asia, farming represents a decreasing share of their income-generating activities, leading to increasing limits to investing family labour in farming. This process has been particularly marked in regions where farmers face limited access to land, water and markets. This study asks whether irrigated farms in central Thailand are on a similar pathway. It analyses how these farms have evolved to face existing constraints and their future prospects. The farms have adapted to constraints including lack of fresh water in the dry season, floods, and sometimes insufficient labour. In almost all farming families, farming is still the main income-generating activity for at least one household member. Most of the farmers involved in fish and shrimp farming had already identified a successor in their family or considered it was possible. This was also the case of rice farmers who had made quite high investments in their farms, most of whom cultivated relatively large areas. However, another group of rice farmers had become trapped in a vicious circle of low farm profitability, the increasing age of the farmers and the fact their farms held little attraction for younger generations. Thai agricultural policies did not provide sufficient means to break this cycle. The future of these vulnerable rice farms thus appears to be uncertain. Breaking this cycle may require a comprehensive approach that explicitly addresses the issue of farm structure.

International audience; Large-scale irrigation schemes, which are often developed in flood plains, overvalue technical expertise and the control of natural hazards and are particularly vulnerable to flooding, but there has been limited study on the impact of floods on irrigation functioning. Using a transdisciplinary approach developed in the Chokwe Irrigation Scheme during the 2013 post-flood recovery period, we analysed the impact of flooding on the scheme with a focus on maintenance. We argue that the flood crisis provided windows of opportunity to reconsider maintenance procedures by rethinking the relations and responsibilities between actors in this large-scale irrigation scheme; but the robustness of the system can only be increased if the changes strengthen the collective action capacity.; Les périmètres irrigués de grande hydraulique qui survalorisent l'expertise technique et le contrôle des risques naturels sont souvent développés dans des plaines d'inondation et donc sont particulièrement vulnérables aux inondations; mais peu de travaux analysent l'impact des inondations sur leur fonctionnement. En s'appuyant sur une approche transdisciplinaire mis en oeuvre dans le périmètre irrigué de Chókwè au Mozambique immédiatement après l'inondation de 2013, nous avons analysé l'impact de l'évènement sur le périmètre en s'intéressant tout particulièrement à la maintenance des infrastructures. Nous soutenons que l'inondation a permis de reconsidérer les procédures de maintenance en réorganisant les relations et les responsabilités entre les acteurs de ce périmètre irrigué de grande hydraulique; mais la robustesse du système ne pourra être améliorée que si ces changements conduisent à renforcer les capacités d'action collective.

Drawing from the experience of the Limpopo River Basin in Mozambique, the paper analyses the articulation of a water rights framework in the context of decentralised river basin governance and IWRM-inspired reforms. The nexus between financial autonomy, service provision, stakeholder participation and the resultant allocation of water within the river basin is explored by scrutinising the newly instituted system of water permits and payments. Three cases are examined: (1) parastatal agencies managing large perimeters of irrigated land; (2) large-scale commercial companies irrigating land; and (3) so-called focal points representing groups of smallholder irrigators. The three presented cases show that structural challenges, local geographies and power relations shape the final outcome of water reforms in relation to decentralised river basin management, stakeholdersʼ participation and accountability. Rather than improving accountability to users and securing the financial basis for sustainable infrastructure operation and maintenance, the permit system in place reinforces existing inequalities.

The study focuses on the assessment of the contribution of sheep and goats to reduce poverty and vulnerability in rural farming systems of three agroecologi¬cal areas in Egypt: the pastoral area of the Northwestern coast (Matruh governo¬rate), the irrigated areas of the Nile Valley (Sohag governorate) and the oasis area of the West Desert (New Valley governorate). An empirical study on 90 farms in the three agroecological areas on different social and economic indicators related to poverty gave indicators on the roles of sheep and goats in different farm types according to resource endowment (e.g. land, livestock, capital) and human resources. The results showed that sheep and goats provided the main source of income to landless and very small land owners to escape the poverty trap. Moreover, the livestock asset generated other sources of wealth that were not taken into account in the monetary poverty approach.

In no other country, perhaps, is the identification between water, irrigation, and agriculture as strong as in Egypt. Several phases of agrarian and technical change throughout its long history have taken Egypt to a situation where farmers grow between one to three crops a year on 3.78 million ha after lifting water from canals and drains, and sometimes from aquifers. This chapter first reviews the extraordinary cost of maintaining the delta 'irrigation machine', the history of irrigated agriculture expansion, and the evolution of public policies. It then examines key issues and challenges, including irrigation modernization, the search for water savings, the multiple experiences with participatory management at various scales, inter-sectoral integration, the water-food-energy nexus, the recent masterplan, and finally transboundary threats.

Dans le périmètre irrigué du Gharb, les tentatives de mise en place des organisations professionnelles agricoles initiées par l'Etat au cours des années 1980 ont généralement abouti à des résultats limités. Ces expériences passées continuent à marquer les discours et les attitudes des agriculteurs et des techniciens qui convergent vers l'impossibilité de mener une coordination réussie impliquant les agriculteurs de la région. Cet article propose une lecture plus globale de l'action collective qui englobe, au-delà des seules organisations professionnelles, l'ensemble des pratiques de coordination pour gérer des ressources productives. A travers une forte immersion dans les vécus locaux dans deux villages, nous avons repéré des pratiques de coordination actives autour de l'eau dans le premier et autour de la culture d'agrumes dans le second. Ces pratiques témoignent de fortes capacités locales de gestion, de négociation et d'innovation. Leur mise en évidence ouvre des pistes pour repenser les méthodes d'appui et d'accompagnement aux collectifs d'agriculteurs. Ainsi, l'accompagnement pourrait plus se fonder sur l'identification des collectifs et réseaux locaux fonctionnels et des projets collectifs existants ou émergents. L'accompagnement à la constitution d'organisations formelles en lien avec les projets collectifs locaux permettrait aux agriculteurs de mieux maitriser leurs relations avec les acteurs extérieurs.

Erratum paru dans Agricultural Water Management (2013) 127 p. 124-126; International audience; This paper reports on an experiment undertaken in the Office du Niger irrigation scheme (100,000 ha) in Mali, where the unprecedented development of irrigation driven by large scale investors is dramatically increasing uncertainty surrounding future water management. Coping with future uncertainty in irrigated systems is essential but existing approaches based on scenarios and decision support systems are mainly expert-driven, making them difficult for local users to understand and use on their own. The aim of this study was to design a participatory approach to help local and national stakeholders understand the possible future consequences for water management of scenarios they had built themselves in previous workshops. A role playing game called FOWIS (Future of water in irrigated systems) was designed for this purpose. Two groups (decision makers and local actors) took part and played the roles of family farmers, large scale investors, or the manager of the irrigation scheme. Playing FOWIS increased the players' awareness of each others' strategies and of land development issues, crop choices, and water management. In the local actors' group, applying land development strategies and choosing crops while failing to account for the inevitable increase in water demand led to serious water crises: total demand exceeded water availability by 75%, and the indicator of adequacy dropped to 0.5 for many players. In the decision makers' group, applying a collective strategy to limit water demand, as stipulated in their best case scenario, resulted in an equitable water supply. In this paper, we show how the game enabled participants to understand the interdependencies between future land development, crop choices, and water management, and, in addition, helped them design innovative strategies to limit water demand or to allocate water fairly. Indirectly, it also led them to question their current practices, choices and strategies that would have been impossible in the current context of open tensions concerning land and water allocation. The FOWIS experiment also provided useful information for the further development of non-computer-assisted role playing games in highly uncertain contexts, which is the case of most irrigated systems in developing countries. RPGs that take place in a virtual world could increase stakeholders' capacities to take action with respect to real world issues. (Résumé d'auteur)

International audience; The use of groundwater in irrigated agriculture is often regarded as an effective way of increasing farm productivity. However, the effects of differential access to groundwater by farmers have rarely been studied at the microeconomic scale, particularly the possibly negative effects of marginalization of small farmers. During the hydraulic crisis that has affected Algerian irrigation schemes since the 1980s, groundwater has become a major source of irrigation for farmers. A process of farm differentiation occurred linked to farmers' access to groundwater, causing social inequity. To understand the differentiation of farms in the Ouarizane irrigation scheme, we first undertook a historical inquiry. Second, we used a participatory prospective approach to analyse possible changes in farming systems after the adoption of a new land reform. Our results confirmed that access to groundwater has become a structural factor in the differentiation of farms and in land concentration in Algerian irrigation schemes. Land concentration and the marginalization of small farmers are likely to worsen when the new land law is applied.; L’usage de l’eau souterraine en agriculture irriguée est souvent considéré comme un facteur d’augmentation de la productivité des agriculteurs. Mais les effets de l’accès différencié à l’eau souterraine ont rarement été étudiés à l’échelle micro-économique et notamment sur d’éventuels effets pervers de marginalisation des petits agriculteurs.Durant la crise hydraulique qui touche les périmètres d’irrigation en Algérie depuis les années 1980, l’eau souterraine est devenue la principale ressource d’irrigation des exploitations agricoles. Un processus de différenciation d’exploitations agricoles en lien avec l’accès à l’ eau souterraine a été enclenché et a entraîné des problèmes d’équité sociale. Dans l’ objectif de comprendre la différenciation des exploitations agricoles dans le périmètre d’ irrigation de Ouarizane, nous avons adopté dans un premier temps une approche d’enquêtes historiques. Dans un deuxième temps, nous avons mobilisé une approche de prospective participative afin d’analyser les trajectoires d’évolution des exploitations agricoles dans un contexte d’adoption d’une nouvelle loi foncière. Nos résultats confirment le rôle structurel de l’accès à l’eau souterraine dans la différenciation des exploitations agricoles et dans le processus de concentration foncière dans les périmètres d’irrigation. Les tendances vers la concentration foncière et la marginalisation des petits agriculteurs vont probablement s’accentuer après l’application de la nouvelle loi foncière.

Etablir des exploitations agricoles viables, de taille moyenne, était considéré essentiel pour mettre en valeur les périmètres étatiques de grande hydraulique. Les agriculteurs étaient encadrées par l'Etat pour 'moderniser' leurs exploitations et produire des cultures industrielles. Ce modèle d'action centralisé a été progressivement démantelé, en particulier par l'installation des forages par les agriculteurs. L'objectif de l'article est d'analyser les trajectoires des exploitations familiales depuis 40 ans dans le périmètre irrigué du Tadla (Maroc) dans un contexte d'utilisation conjuguée de l'eau. Les résultats ont montré que ces trajectoires sont liées à l'accès à l'eau souterraine, mais aussi aux marchés (informels) fonciers et aux revenus hors-agricoles. Depuis les années 1980, l'eau souterraine a permis aux agriculteurs de compenser le déficit d'eau de surface et de diversifier les assolements. Cependant, ce sont essentiellement les grandes et moyennes exploitations (36% du nombre total) qui ont pu accéder à l'eau souterraine. Ces agriculteurs ont également augmenté la surface cultivée à travers les marchés fonciers. Les petits agriculteurs prennent peu de terres en location, car il faut du capital pour louer et mettre en valeur la terre. En outre, seulement 20% des petites exploitations accèdent directement à l'eau souterraine. L'eau souterraine montre ainsi peu de capacités redistributives. Les revenus hors-agricoles ont permis de compléter les revenus agricoles, qui peuvent être négatifs, en année sèche. Cependant, ces revenus ne sont guère investis en agriculture. Finalement, l'eau souterraine mobilisée depuis 40 ans provient principalement des aquifères phréatiques, régulièrement rechargées par les eaux de pluie et l'irrigation de surface. Son exploitation semble durable pour l'instant, mais les agriculteurs explorent les aquifères plus profondes, alors que l'administration encourage la conversion de superficies importantes vers l'irrigation localisée, ce qui réduira la recharge des aquifères et pourra rendre incertain l'avenir des agricultures irriguées à partir des eaux souterraines.

Les systèmes irrigués collectifs sont communément confrontés à de faibles performances de l'irrigation à l'échelle de l'aménagement. Une étude détaillée a été réalisée dans un périmètre oasien du sud tunisien pour évaluer les performances de la gestion de l'irrigation à l'échelle de l'oasis et de la parcelle. Les données ont été collectées auprès de l'association des usagers de l'eau et sur la base d'une vaste campagne d'enquêtes et d'observations afin de quantifier les causes des faibles performances de l'irrigation. A l'échelle de l'oasis, les résultats montrent que la durée du tour d'eau excède le double de celle prévue par les règles collectives (19 à 21 jours). La principale cause est la durée excessive des irrigations qui atteint presque le double de la règle de 10 h ha?1, due à des pratiques individuelles inappropriées à l'échelle de la parcelle. L'influence modérée de l'extension des superficies irriguées et des dysfonctionnements techniques du réseau est par ailleurs compensée par l'absence ou l'annulation occasionnelle de l'irrigation dans certaines parcelles.A l'échelle de la parcelle, les durées excessives des irrigations sont le résultat d'un effet conjugué des parcelles de petite taille, du mauvais entretien du système d'irrigation, des irrigations nocturnes sans surveillance et de la faible implication du propriétaire. Cette situationmet l'accent sur l'efficience et la durabilité des systèmes irrigués quand les agriculteurs ne respectent pas les règles collectives et, dans le cas de systèmes oasiens, étendent les plantations de palmiers.De plus, la situation souligne lemanque d'équité qui restreint le soutien apporté par les agriculteurs à l'association des usagers et la stricte application des règles de gestion. Ces résultats devraient permettre d'identifier une approche appropriée et conduire à des changements positifs dans la gestion des systèmes irrigués collectifs.

Locusta migratoria cinerascens became a potential pest in irrigated cereals under pivots, in the Touat region (Algerian Central Sahara), since the indication of the fi rst crowding in June 1994. Morphometrics and bioclimatic approaches revealed the homogeneity between North and South Algerian populations, suggesting a recent colonisation of Central Sahara, aided by the development of large acreage perimeters. We studied the populations of this acridian from 1995 to 2004 and show that they belonged to the solitarious or transiens phase and never reached the gregarious one. The absence of this last phase is discussed in the light of heterogeneous densities observed in the successive generations. Resume. Populations centre-sahariennes de Locusta migratoria cinerascens (Orthoptera : Acrididae) dans les perimetres irrigues : est-ce une colonisation recente ? Locusta migratoria cinerascens est devenu un ravageur potentiel dans les cultures de cereales irriguees sous pivots, dans la region de Touat (Sahara Central algerien), depuis l'indication des premieres pullulations en juin 1994. Des approches morphometriques et bioclimatiques revelent une homogeneite des populations du nord et du sud algerien, suggerant une colonisation recente dans le Sahara Central, a la faveur de la mise en valeur de grandes surfaces agricoles. Nous avons etudie des populations de cet acridien de 1995 a 2004 et montrons qu'il s'agit d'individus de phase solitaire ou transiens, n'ayant jamais atteint l'etat gregaire. L'absence de cette derniere phase est discutee a la lumiere des fortes variations de densites observees entre les differentes generations.

For many years, large-scale irrigation around the world was based on state-driven water management and on a planned innovation process and diffusionist extension services. The purpose of this study is to show that formal extension services are not the only intermediaries of innovation and that local innovations take place at the initiative of farmers even in state-driven irrigation schemes. The study addressed changes in farming systems in a large-scale irrigation scheme in Morocco from two angles: a review of planned innovations and analysis of the actual innovation process at the village level. We show that the implementation of the large-scale irrigation scheme contributed to agricultural development, but often indirectly, and that it was not the only source of innovation. We also show how these results support recent thinking on innovation systems. Today, informal labour, neighbour and marketing networks are the main innovation intermediaries. New practices in agricultural extension are required to facilitate local innovations and to link farmers to more global innovation networks.

International audience; Ce travail qui a pour objectifs la comparaison des indices d’efficiences économiques des exploitations agricoles irriguées. La méthode Data Envelopment Analysis (DEA) a été adoptée. Un échantillon de 49 exploitations a servi de base à cette étude. Il englobe des exploitations avec des systèmes de production différents (Maraîchers, céréaliers, agrumicoles et sucriers) et des modes d’irrigation différents (Localisé, aspersion et gravitaire). L’analyse des données montre que parmi les exploitations les plus efficientes on trouve en même temps celles qui «souffrent» d’un manque d’eau d’irrigation (zone du Beht) et celles qui ont un accès illimité à la ressource (pompages privés au niveau de la zone côtière). 73% des exploitations de l’ensemble de l’échantillon sont inefficientes. Ce qui montre que la majorité des agriculteurs ne maîtrise pas la technologie disponible. The aims of the present study were to calculate and compare the economic efficiency indices of irrigated farms and the level of valorisation of the irrigation water used by the main crops grown in the Gharb perimeter. To this end, the Data Envelopment Analysis (DEA) model was used to calculate efficiency indices. The survey covered 49 farms with different farming systems (vegetables, citrus crops, cereals, forage, sugar beet and sugar cane) and different irrigation systems (drip, sprinkler and gravity). The results showed that the most efficient farms were those that "suffered" from lack of irrigation water and not those that had "unlimited" access to the water resource (private pumping). On the other hand, 73% of the farms surveyed were inefficient, indicating that the majority of farmers do not use the available technology correctly.

International audience; The relationship between irrigated schemes, farms and agro-food processors may provide leeway to improve water saving and water productivity. This study was conducted in the dairy supply area of the Tadla irrigation scheme in Morocco and in the oasis area in southern Tunisia where dates are grown for export. The study was based on (i) a framework conceptualizing the relationship between production/marketing of agricultural raw material and water saving and productivity and (ii) a participatory research method aimed at supporting stakeholders in solving their production problems. Analysis of the organization of the two supply chains revealed the central role of intermediate operators in aggregating raw material and providing services to farmers. A decision support approach for dairy farmers was designed and tested in the Tadla scheme. Its use is illustrated by four scenarios that simulate the impacts of changes in both forage crops and irrigation techniques on farm income and water consumption and productivity. Lessons drawn from this work concern support for stakeholders and the integration of production functions from the irrigated scheme to the agro-processors in the whole supply chain.; Les relations entre périmètres irrigués, exploitations agricoles et filières agro-alimentaires représentent un levier d’action potentiel pour améliorer l’économie et la valorisation de l’eau d’irrigation. Cette étude conduite dans le bassin de collecte laitier du Tadla au Maroc, et le bassin de production de la datte d’exportation dans le Sud Tunisien, se base sur un cadre conceptualisant le lien entre les variables de production et de commercialisation de la matière première agricole et les notions d’économie et de valorisation de l’eau. Elle mobilise une démarche de recherche intervention visant a` aider les acteurs dans la résolution de leurs problèmes. L’analyse du fonctionnement des deux chaînes d’approvisionnement souligne l’importance des opérateurs intermédiaires entre agriculteurs et opérateurs aval pour agréger la matière première et fournir des services aux agriculteurs. Une démarche d’accompagnement des éleveurs laitiers a été expérimentée sur le Tadla. Son utilisation est illustrée par la simulation de quatre scénarios articulant des changements de cultures fourragères et de techniques d’irrigation. Les leçons tirées de cette expérience concernent tant la démarche proposée que l’intégration des fonctions de production au sein de la chaîne d’approvisionnement, depuis le gestionnaire du périmètre jusqu’aux opérateurs aval.

Multivariate analyses were used to compare dairy production practices and their consequences on milk yield and profitability in cattle farms from two representative regions of Morocco. A regular follow-up of 118 farms (48 in the Rabat-Sale suburban belt and 70 in the Gharb irrigated perimeter) was undertaken to obtain accurate data. Results show significant differences between the two regions. Intensive milk production was more frequent in the suburban zone (more concentrates and better annual milk yield per cow). When conducting a “within-region” principal components analysis, farms’ discrimination appeared to take into account all management variables (feeding, cattle sales, profitability), with no reference to farms’ structural parameters (arable land and number of cattle). A typology of farms was then established using cluster analysis, with 4 distinct groups, namely: a) concentrates wasters, b) farms with a relatively important milk yield per cow, c) deficit dairy farms and d) beef oriented farms. The last group included almost exclusively farms from the irrigated perimeter (5 out of 7). These results indicate that dairy production promotion in Morocco requires more than just the intensification of forage production, but should focus also on improving management practices. The extension of complete and balanced dairy rations is urgently needed to enhance milk yield and profitability.

In the former bantustans of South Africa, most smallholder irrigation schemes, although moribund, are earmarked for rehabilitation and management transfer. Although such processes are backed-up with important means, it remains difficult to evaluate the schemes' prospects and potential in terms of financial viability and overall sustainability. Besides, beneficiaries are hardly prepared to take over management at both farm and scheme level, as they lack technical and managerial skills, capital and markets, in a context of unclear property rights over resources, dependency and individualism. The paper briefly describes such situation, and then presents a multi-disciplinary, action-research approach that has been developed to address such issues. It first describes the approach, which makes use of a tool, Smile, as a database, as a model and as a simulation platform. The paper then describes a participatory and heuristic application of the approach, using examples from a recent case study. The process first involves a quantitative, technical, and economic diagnosis of the scheme. Crop and farmer typologies are established, validated by the management committee members, and then captured into the Smile platform. Workshops are then organized in order to collect questions, ideas and scenarios worth-testing. In a recent case study, the following areas have been addressed: bulk water supply, farming systems, land re-allocation, water charging system. The results of several simulations and action-research projects show that crop diversification and intensification are the current best options towards cost recovery and the viability of SIS, in a context of limited resources. Clarification on land rights, and some form of land reallocation towards willing farmers should also help. Results also demonstrate that both diagnosis and simulations prompt collective learning and participation by farmers. First, the diagnosis allows them to collectively talk, reflect and agree on the current situation and issues. Second, the prospective and heuristic analysis through scenario-testing helps to define longer term strategies for the scheme, and to identify development pathways that are documented and discussed. Such an approach shows huge potential for the information of transfer operators, and for farmers' training, participation and empowerment.

Within a context of limited water resource, the irrigated perimeters of the leeward coast of the Réunion Island (Département français d'Outre-Mer, Indian Ocean) are today facing a growing competition with the urban users. The priority given to drinking water supply and the emergence of concerns for the protection of aquatic zones question the level of water pumping for agriculture and current irrigation practices. The "Gestion de l'eau (Water Management)" and "Systèmes canne à sucre (Sugar Cane Systems)" URs of the Grad associated with the "Irrigation" UR of the Cemagref are implementing an agronomic and economic integrated approach at the different scales of cultivated plots, of the farm, and of the irrigated perimeter as a whole, to deal with the issue of the achievable water savings. The irrigated perimeters studied are characterised by a wide diversity of production structures and pedo-climatic factors. The method used intends to take this diversity into account through a zoning of the physical environment and of the water needs for the crops, and through a typology of the farms. The analysis and the modelling of the behaviour of the irrigators tries to explain the excess water consumption with respect to the optimal needs and to report on the means necessary to achieve potential water savings. The approach combines a modelling of the irrigation control rules to assess the water demand at individual level and an economic modelling of the agricultural offer (and of the demand in derived water) at the scale of the irrigated perimeter. (Texte intégral)

The small irrigated perimeters in South Africa currently face major problems: lack of local organisation, institutional weaknesses, limited access to most of the markets, etc. Despite numerous unsolved challenges, the central and provincial auhtorities have initiated a water management transfer and rehabilitation process. Within this context, the SMILE (Sustainable Management of Irrigated Land and Environment) project, conducted by the Gestion de l'eau (Cirad) UPR, supports this rehabilitation process through research-action at the local level. This project is being carried out in close partnership with the local decision-makers. Its objective is to support decision making and planning, to help groups of users in their role as managers, and to set up a common platform for discussion, training, awareness raising, and capacity building. The approach calls for data collection and analysis at the level of the perimeters, the definition of typology regarding the cultural and agricultural systems, and the use of a software to store data and test different scenarios. For this, a simulation platform (SMILE software) has been developed that enables future work to be carried out analysing of the current situation and subsequent scenario testing that simulates technical, economic, institutional, legal or socio-economic changes, as discussed with stakeholders. (Texte intégral)

Lors de la mise en place de nouveaux périmètres irrigués ou de leur modification, il est nécessaire de prévoir les besoins en eau d'irrigation sur la surface considérée. Ceci permet d'ajuster les surfaces à la ressource, de choisir les spéculations, de dimensionner les dispositifs de distribution. A la Réunion, en réponse à une demande des décideurs relative aux nouveaux périmètres de l'ouest de l'île (besoins en eau d'irrigation et débits de pointe), une modélisation du bilan hydrique a été réalisée. Ces besoins en irrigation dépendent, certes, du climat (pluie, ETP) mais aussi de l'évapotranspiration des plantes, des capacités de stockage de l'eau dans le sol, des modes d'irrigation et de l'efficience du matériel. L'outil (SIMULIRRIG), prend en compte ces paramètres. Il est couplé à une base de données météorologiques et simule le fonctionnement hydrique de parcelles virtuelles ou de combinaisons de parcelles. On en tire le déficit journalier en culture pluviale, puis les besoins en eau d'irrigation. Une analyse fréquentielle permet d'estimer, par décade, mois et année, ces volumes, en année médiane et sèche (1an/5) et d'estimer les débits de pointe (litres/seconde) relevés durant la décade la plus sèche de la série climatique. La modélisation a été réalisée sur 19 sites de l'ouest de la Réunion près des postes météo disponibles. Il est possible de relier, dans les conditions locales, les besoins en eau d'irrigation (volume, débit) à l'altitude, ce qui permet des interpolations. (Texte intégral)

Les zones irriguées des bas de la Réunion constituent l'aire privilégiée de culture de la canne à sucre compte tenu des niveaux élevés de productivité atteints avec la maîtrise de l'eau. Le développement de l'irrigation, au-delà d'un objectif de productivité pour la canne à sucre, répond aussi à un objectif social d'emplois. En effet, l'aménagement des périmètres irrigués dans le sud a accompagné une réforme foncière qui a permis l'installation de plusieurs centaines de petites exploitations familiales. Ce modèle d'exploitation issu de la réforme foncière qui reposait à l'origine sur une quasi-monoculture de la canne à sucre est aujourd'hui remis en cause par une rentabilité insuffisante pour des petites surfaces. La diversification agricole apparaît comme une voie intéressante, alternative à l'agrandissement, mais des questions se posent quant à ses modalités et ses effets en termes de compétition ou complémentarité avec la canne à sucre. Cet article examine les conditions d'insertion de cultures maraîchères, fruitières, fourragères et d'activités d'élevage dans les exploitations à base de canne à sucre, et les performances comparées de ces opportunités de diversification. Une enquête menée auprès d'exploitations des deux périmètres irrigués du Sud montre des voies différenciées de diversification. On distingue, en effet, des systèmes de culture qui visent la complémentarité avec la canne à sucre en se calant sur les périodes creuses d'inter-coupe, des systèmes plus intensifs où le travail est affecté prioritairement aux activités de diversification et enfin quelques rares systèmes spécialisés sans canne à sucre. L'analyse porte sur les facteurs d'adoption de ces cultures de diversification. On relève comme facteurs prépondérants au niveau de l'exploitation, la relation à la main-d'oeuvre salariée et la capacité d'investissement, et au niveau de son environnement, l'accès à des débouchés sécurisés et l'encadrement technique. (Texte intégral)

Over the past three decades, public irrigation schemes have been exposed to a process of management transfer from the central government and the funding agencies to local entities such as water users' associations and districts. However, this management transfer has been in many cases poorly implemented. Frequently reported problems are: inappropriate design; poorly specified management functions; ineffective accountability; unclear ownership of the collective infrastructure, and a lack of support services for achieving the transfer of management with success. In the Petrolina-Juazeiro region in the Northeast of Brazil, the CODEVASF (Company for the Development of the Valleys of the São Francisco and the Parnaiba Rivers) has started to gradually transfer the management of public irrigation schemes to districts or local management entities. The districts are responsible for every day management, but they also need to make strategic decisions that affect the sustainability (technical, financial, socio-economic, environmental) of the irrigation schemes in the long run. This dissertation was set up in the irrigation projects of Mandacaru and Maniçoba, to analyse the scheme management by the main internal stakeholders (scheme manager versus farmers), as well as to support them to solve problems and to plan ahead. The research focused on the interaction between the scheme manager's water supply and the farmers' water demand, since it is the central function inside the irrigation scheme.[...] A simulation model was developed to support the stakeholders' reflections on alternative plans of the water supply and demand. The modelling of the collective water supply is limited to its main infrastructure and organizational parameters. The collective water demand is modelled by using a farm typology that gives a simplified representation of the diversity of the farms in the irrigation scheme, as well as their water demands. The main output of the model is the coverage of the water demand by the water supply at scheme level. The aim of the modelling approach was to provide support to stakeholders so that they can simulate and evaluate prospective scenarios of the water demand and alternative plans of the water supply, for example the possibility to increase the water supply by organizing water delivery to farmers at night [...] Further analysis of the real contribution of this type of decision support methods in the stakeholders' learning process of irrigation management needs to be undertaken on other case studies, so as to evaluate their real interest and transferability to other specific situations of irrigation scheme management.

CIRAD, HJRBDA and NAERLS undertook a collaborative programme on the Hadejia Valley Irrigation Project to strengthen the agency and the Water Users Associations (WUAs) in their roles and to ensure an efficient transfer of responsibilities from the agency to the farmers. In the scope of the implementation of the Agency/fanner Joint Management concept, stakeholders decided to develop an information system able to provide information for the assessment of the system. The tool aimed to promote the discussion and negotiation between project managers and WUA leaders. The tool is composed of a relational database and a Geographical Information System (GIS). Technically four databases were created to get faster response time. Data entry, storage and analysis are done from a user-friendly interface. Making queries using Mapinfo software automatically generates tables and charts about the irrigation scheme performances. The GIS stores the spatial (Geographical) data. It enables users to represent information like cropping intensities, weed infestation etc, on maps. The development of the information system was iterative and it has been finalized base on field situation and users needs. Training sessions were organized to ensure an efficient transfer to all the collaborating partners and four HVIP staff. The real impacts of the information system are the applications made. Currently agency and farmers use the information system for diagnosis, monitoring and evaluation, discussion and negotiation, and provision of information at policy level. Because of the obvious benefits of the information system the collaborating partners plan to extend the experience to other sites in the country.

An integrated approach was used to introduce the agency-Farmer-Joint-Irrigation-Management (AFJM) concept in Hadejia-Valley-Irrigation-Project (HVIP). The intervention was undertaken between 1996 to 2002 covering a period of eleven cropping seasons (i.e. 6 wet and 5 dry seasons). Specific modules in the areas of system operation network maintenance, and agricultural production and marketing were designed and presented to the agency and users for familiarization and use. This was undertaken in two stages. First stage involve preparation of farmers seasonal plans based on wishes and expectations, while the second stage involve joint revision of the seasonal plans by both agency managers and users through negotiation, prioritization, available resource to reflect field realities. Results from the intervention revealed that both the Irrigation Agency (IA) and Water Users Associations (WUAs) adopted the AFJM concept at varying degrees. The IA was reorganized resulting in the creation of a WUA unit where activities relating to WUAs are organized and co-ordinated. This organizational reform enabled the IA to improve its Manpower quality ratio (MPQR), Financial Autonomy Factor (FAF), and Financial-Self-Sufficiency-Factor (FSSF) from means of 20.0, 0.0, and 14.7% to means of 24, 14.0 and 26%, respectively. The IA also witnessed increase in Cost Recovery Ratio (CRR) from a mean of 47 to 72%. Farmers were similarly organized into eight functional WUAs registered with Local and State Governments. The WUAs grew in membership from a mean of 82 to 146 per association from which an Internal Revenue Generation (IRG) of 58% was achieved. A mean Financial Viability Index (FVI) of 40% per WUA was also attained. Assessment of the AFJM concept showed that the approach necessitated improvement in the quality of irrigation services rendered by the irrigation agency. It also provided the needed incentive for effective user participation, which led to joint sharing of costs and responsibilities. The framework and methodology used also provide an effective tool for investigation of wide scheme management interventions and policy issues.

Nigeria witnessed a rapid expansion of irrigate area between late 1970's to late 1980's where over 100,000 ha were developed under the supervision of government agencies (Nwa, 1983). This was seen as socio-political strategy to combat the devastating drought of mid 1970's and means of providing employment for the teeming population, among others (Olofin, 1993). The Government however found it difficult to finance the recovery costs of running these schemes mainly due to decline in allocations and low recovery from water fees. Olugbemi 1993 reported that 45% cost recovery form water charges was the highest ever recorded in the country. Centrally financed procedures of the agencies tend to hinder the effective provision of quality services to farmers (Musa, 1997); - These and other factors led to the rapid deterioration of infrastructure, shrinkage of area irrigated, maldistribution and wastage of water. By 1999 the total irrigated area under the supervision of the agencies dropped to less than 30,000 ha (Musa, 1999). Driven largely by financial pressures the government started contemplating to share management responsibilities of irrigation schemes between these agencies and the users organised into associations.

The idea of "Participatory Irrigation Management (PIM)", is aimed at enhancing capacity building or local empowerment of the irrigation users'. It will also promote sustainable management of irrigation systems. It requires an , institutionalized arrangement by establishing a formal mechanism for interaction between farmers and the irrigation agency. This has to be done through an organized channel such as Water Users' Associations (WUAs). The WUAs when established, will discuss, negotiate, participate in decision-making and mobilize resources towards operation and maintenance with the agency on issues concerning irrigation management. If WUAs are established, the role of the irrigators as an organized group becomes very important. Major decisions regarding irrigation management would be taken by the irrigation organization composed of farmers' representatives who should be formally elected by members for a definite tenure. Ostrom (1993) reported that "the WUAs would have the characteristic of (a) direct involvement of the irrigators, (b) effective monitoring and sanctioning, and (c) holding officials accountable". The WUAs when established would become self-regulating, self-supporting, and self-governing on issues concerning irrigation management, whereas the irrigation agency will play a regulatory role. The WUAs would be responsible for all day -to -day activities on operation and maintenance of the irrigation system. For an irrigation system to effectively operate, users must have the organizational capacity to (i) maintain the physical facilities in terms of operation, maintenance, construction and design of the system, (ii) look into the system performance through efficient management considering conflict resolutions, communication, resource generation, and decision making, and (iii) co-ordinate water use activities with respect to acquisition, allocation, distribution and drainage management. Therefore, PIM helps in promoting self-reliance, social justice, peoples' organization, and capacity building on irrigation management issues. One means by which PIM can successfully be achieved is by moving away from conventional agency dominance in management, towards participatory approaches that combine the social experience, sharing of knowledge and understanding of irrigation users or farmer groups as a unit.

Over the past three decades, the various governments in Nigeria have put constant efforts on promotion and development of modern irrigation scheme, as a way to increase food production and meet an ever-increasing demand. Despite all the investments put into development of large irrigation schemes, the overall performance of most of the latter have been below expectations (Kaliel, 1999). Hadejia Valley Irrigation Project (HVIP) had been recording low performance of dry-season irrigation activities since its inception in 1993. An average dry season cropping intensity of 16.3% had been recorded over the past six years (Kura, 2002). This scenario forced policy makers financiers to question issues such as returns on investment, and challenged researchers to uncover the reasons for the low performance. To accurately determine and appreciate the reasons for the low dry season cropping intensity, a better understanding of the context in which irrigation activities are carried out is needed. Irrigation activities are embedded within broad socio-economic and agro-ecological settings that strongly shape the farming system. In HVIP, other farming systems such as upland farming, fadama farming, cattle rearing and fishing. activities were existing before the inception of the irrigation scheme. I lence irrigation activities were added to the existing ones. Irrigation activities are therefore taking place within a complex system involving other activities that may influence, compete or complement its demand for finance, labor, input distribution, time and management. These conditions of production contribute in shaping the diverse strategies adopted by farmers in their production activities. Any intervention aimed at improving the cropping intensities and subsequently farmers' income has to clearly identify and target the different types of farmers. This paper examines the integration of irrigation farming into other farming systems using a typology to classify farmers who adopt similar strategies in the integration of these farming systems.

The sustainability of self-governing irrigation schemes is currently under pressure in many countries as public financial support is decreasing. Furthermore, growing global concern regarding water scarcity means that efficient water use is essential. Theoretically the choice and implementation of a water-pricing system should play a central role in achieving this objective, both by recovering water costs and by encouraging farmers to adopt more efficient behaviour. In the Senegal River Delta newly established water users associations (WUAs) have chosen low water charges, which are affordable for the majority of fanners but which underestimate long-term maintenance costs. Combined with the difficulty of collecting and managing fanners' fees, this choice has drawn them into a vicious circle leading to scheme deterioration and poor water service. New alternatives have been discussed with them using a simulation tool that takes into account both the water costs and the farmers' incomes. Compared with the present fixed water charge based only on cultivated land, a twopart option based both on equipped and irrigated areas ensures the recovery of fixed expenses such as maintenance, while encouraging farmers to intensify their farming systems by adopting double cropping. Nevertheless choosing a relevant water charge does not ensure by itself the sustainability of an irrigation scheme. Combined support providing WUAS and farmers with efficient advice regarding management and organisational skills should also contribute significantly to achieve this prime objective.

Government smallholder irrigation schemes (SIS) were developed in former homeland areas of South Africa during the apartheid era, mostly for community food supply purposes. The parastal entities that used to support them have gradually collapsed from the early 1990's. These schemes are now facing serious problems and an uncertain future, owing to low yields, deteriorating infrastructures, limited access to services, weak and unclear institutions regarding water and land, and lack of support. Although representing a small percentage of irrigated land at country level, their location in deep poor rural areas represents a potential for poverty alleviation and food security in such areas. The central and provincial governments aim to both revitalise SIS and curtail the financial burden of their maintenance and operation costs. Most schemes are earmarked for rehabilitation and transfer to users' associations in the Northern Province and the Eastern Cape Province. In recent years, many countries have embarked on a similar process to transfer the management of irrigation systems from government agencies to water users associations (or other private sector entities). However, most professionals involved are still unsure about whether to adopt reforms and how to design and implement them. In South Africa, it is very difficult for decision-makers and operators to evaluate the potential for long-term sustainability, then to organise rehabilitation and transfer accordingly, owing to a context of low participation, weak local institutions, and lack of information regarding farmers' strategies, land tenure arrangements, cropping systems, household socio-economics, and so on, which eventually determine the potential for cost recovery and economic viability. A research team from CIRAD and the University of Pretoria proposes an action-research approach of SIS, in three steps: - Collecting information on the socio-economic and technical circumstances at household and scheme level; - Capturing data into a model that calculates both the costs incurred by scheme management, and the possible contributions by farmers to cover these costs in a context of management by a water users' association; - Running the model on a scenario-testing basis, evaluating the impact of certain measures or decisions, or certain farmers' strategies. [...].

An integrated approach is developed to assess the effects of joint irrigation management by agency and users on system operation and maintenance, agricultural productivity, farmer income, cost recovery, and sustainability. The approach was tested in a 2,150 ha irrigation system, Hadejia Valley Irrigation Project (HVIP) located in the Sudan Savannah ecology. The scheme is in Hadejia Emirate of Jigawa State, Northern Nigeria where only canal water is used for irrigation. The main objective of the study is to involve farmers, through the Water Users' Associations (WUAs), in decision-making and management of the irrigation scheme. This is expected to enable the agency provide quality services leading to both higher crop productivity and farmer incomes, thus recovering the O & M costs for the sustainable use and management of the irrigation scheme. The study revealed that both the Irrigation Agency (IA) and Water Users Associations (WUAs) adopted the Agency Farmer Joint Management (AFJM) concept at varying degrees. The IA was re- organized which resulted in the creation of a WUA unit where users' activities are organized and co-coordinated. [...] The assessment of the applied AFJM concept showed that the approach allowed improvement in the quality of irrigation services rendered by the Agency as well as providing the incentive for user effective participation and sharing of cost and responsibilities. The framework and methodology used also provide for investigation of wide scheme management interventions and policy issues.

International audience; Evaluation de la salinisation dans le périmètre irrigué de Maniçoba. Depuis la mise en opération du périmètre irrigué de Maniçoba, situé dans le nordeste semi-aride du Brésil, environ 10 % des terres ont été abandonnées. Des échantillons de sol ont été prélevés sur dix-huit parcelles où la salinisation des sols est invoquée par les producteurs comme raison principale de leur abandon. Les objectifs étaient de vérifier cette hypothèse par la collecte de données quantitatives, et de déterminer l'origine et la distribution spatiale de la salinisation. Des prélèvements de sol ont été réalisés en zone abandonnée, en zone cultivée et irriguée, ainsi que sur des sols encore non exploités. Les résultats confirment le problème de salinisation dans la plupart des parcelles abandonnées. En l'absence de sels géologiques, et l'eau d'irrigation étant d'excellente qualité, il est assumé que la salinisation résulte de la concentration de fertilisants lessivés dans certaines parties du périmètre. L'hétérogénéité du sous-sol, l'existence de bassins souterrains et de couches imperméables peu profondes, représentent des risques de nappe phréatique superficielle et de salinisation dans ces parties. Néanmoins, ces contraintes ne semblent être prises en compte ni dans l'élaboration de politiques de préservation des sols ni dans les programmes d'assistance technique.

The recent success of agricultural production in the Office du Niger irrigation scheme in Mali, linked with the modernisation of this scheme over the past twenty years and facilitated by a favourable economic and institutional context, has prompted a debate on the opportunity to extend this 74,000 ha system. The views of the different stakeholders converge on the necessity to have more irrigated lands, but there is a passionate on-going debate on the objectives of the extension - producing more rice for domestic consumption and the export markets or providing the necessary conditions to ensure the viability of the existing farm holdings - and on the planning and implementation of this extension programme. This latter aspect relates principally to the financing of the extension programme, the land tenure status provided to farmers, sharing the water of the Niger river, and to the environmental impact of these extensions. The paper illustrates how the extension of the irrigation system should be integrated in a larger regional rural development planning process.

Le Nigeria entend impliquer des Associations d'Usagers de l'Eau (AUE) dans la gestion des périmètres irrigués publics, qui sont actuellement gérées entièrement par des agences de bassin (RBDA). La gestion participative des périmètres irrigués ou Gestion Participative de l'Irrigation (PIM) est l'objet d'un projet de recherche-développement entre le CIRAD, le NAERLS et le HJRBDA dans le périmètre du Hadejia Valley (HVIP). Les expériences acquises lors du projet ont été débattues pendant un colloque national, rassemblant plus d'une centaine de professionnels, de chercheurs et de représentants des AUE, du 26 au 30 mars 2001 à Zaria, organisé par le NAERLS et le ministère fédéral des ressources en eau. Le but du colloque était de parvenir à un consensus sur les objectifs et la mise en oeuvre de PIM dans toutes les agences de bassin afin d'obtenir un soutien politique pour l'implication des AUE dans la gestion des périmètres irrigués et de contribuer à l'élaboration d'une législation sur cette gestion participative. Une première version d'un cadre directeur pour la mise en oeuvre de PIM dans les périmètres irrigués a été débattue. Ce cadre sera revu à la lumière des remarques faites par les participants et un manuel sera également élaboré. Ces documents serviront comme base pour les RBDA pour impliquer les AUE dans la gestion des périmètres irrigués et contribueront à l'élaboration d'une nouvelle loi sur l'eau, débattue dans l'Assemblée Nationale du Nigeria. Le programme 2001 du projet CIRAD-NAERLS-HJRBDA répond bien aux attentes des institutions nigérianes, exprimées lors du colloque du fait que nous avons proposé d'élaborer une synthèse de nos expériences d'intervention au HVIP et que nous avons élargi notre champ d'intervention au périmètre du Kano River (KRIP). Pendant la mission les activités du projet ont été revues en détail et les activités de 2001 planifiées, en consultant mieux les AUE sur le contenu des interventions. Finalement, un CSN, basé à Zaria, a démarré ses activités dans le projet et a été introduit auprès des différents partenaires. Un programme d'activités a été élaboré.

What makes South Africa an interesting case of IMT is that it takes place along with the implementation of a new water policy. Equally challenging is the fact that IMT involves a series of very different situations, from commercial and exporting large-scale irrigation schemes, to smallholding developing, and subsistence-based irrigation schemes. This paper briefly reviews the situation of smallholding irrigation schemes -SIS- in previously disadvantaged rural areas of South Africa It then analyses the implication of the new National Water Act of 1998 on those schemes, with regard to the IMT process. An analysis of water rights related issues is proposed. It highlights a number of contradictions, uncertainties and possible threats which may hinder further development, and sustainable IMT in SIS. Since 1994, the South African Government has undertaken massive reforms aiming at addressing rural poverty and inequalities inherited from the past apartheid regime. Amongst other programmes, it adopted an ambitious new water legislation, which promotes equity, sustainabilitity, representativity and efficiency through water management decentralisation, new local and regional institutions, water users 'registration and licensing, and the emergence of water rights' markets. At the same time, it adopted liberalism as economic and developmental guideline. Direct consequences are: State withdrawal from its former commitments and controls, liberalisation of markets, decentralisation, transfer of competencies towards local management and decision structures. IMT partakes to this process. All this also generates a major dilemma for a government under budget constraints and social pressure, i.e. matching a social, right-based, gap-filling and developmental approach with a productivity, economic efficiency approach. Such an issue is reflected in the tricky circumstances currently facing SIS and the IMT process in South Africa.

This study has been carried out in two irrigation schemes of the Northern Province (Dingleydale and New Forest) of South Africa. The studied area takes place in former homelands areas (Lebowa, Gazankulu). This region is submitted to a sub-tropical climate. The infrastructures were built during the apartheid era, in order to provide employment and food to the local black population. Currently, the farmers crop from 1 to 10 hectares, producing maize in the summer and vegetables, mainly in winter. Following the National Water Act of 1998 and its new institutional frame, the South-African government tends currently to Withdraw from its ownership and commitments in small-scale irrigation schemes. Ownership, management and maintenance of infrastructures are to be transferred to farmers (Irrigation Management Transfer process). In the Northern Province, this process has started in several pilot schernes. It includes the rehabilitation of infrastructures before transfer and the establishment of farmers' Water User's Association, wlùch are to take over ownership and collective management of the scheme. This study has been carried out in collaboration with the consultant team in charge of the ITM project. The report first considers the evolution of the agrarian system during the 20th century. It shows declining soil fertility. due to the increasing disconnection between agriculture and cattle rearing, and to the remoteness of the cultivated plots. Then, the diversity of the farmers' situations has been highlighted through the use of typological techniques, Nine household types have been identified within the schemes, and thorough economic analysis has been carried out. Particularly, some -vulnerable types of farmers have been identified, whose plight might worsen after the transfer. On the other hand, efficient and dynamic farms have also been detected. They might become bigger and more integrated within commercial circuits. The management of water distribution has also been studied. It reveals a lack of both discipline and organisation. This might slow down the project's development, and., ultimately, jeopardize the scheme's sustainable management. Finally, the study of neighbouring communities has highlighted the gap between this social and economic environment and the scheme itself The latter have long received subsidies and guidance, while communities have been left without any kind of support whatsoever, and display poverty and unemployment features.

Bien qu'il soit perçu comme une nécessité, le développement de l'irrigation en Afrique de l'Ouest est actuellement très limité. Les succès économiques des projets d'irrigation existants ont amené les commanditaires à réduire considérablement leurs investissements. Il faudrait privilégier la restauration des terres existantes plutôt que d'augmenter la surface des zones irriguées et surtout redéfinir un nouveau climat institutionnel et socio-économique de manière à favoriser la création d'organisations d'exploitants capables de gérer les projets d'irrigation à long terme. Compte tenu des dernières expériences dans ce domaine, les chercheurs s'interrogent sur les conditions susceptibles de permettre la création de telles organisations d'exploitants

L'irrigation informelle s'est largement développé dans le Delta du Fleuve Sénégal depuis 1988. Cette étude à pour but d'analyser les possibilités et les conditions pour les agriculteurs et le secteur privé de remplacer l'Etat dans le développement de l'irrigation. Elle présente les résultats obtenus après un suivi de 2 années de six organisations paysannes. Malgré, une grande diversité de situation, terres, équipement, organisation, des problèmes agronomiques similaires entraînent des rendements relativement bas. Les performances sont plus faibles sur les périmètres informels que dans les opérations à grandes échelles. Une nouvelle conception des périmètres, une meilleure définition des responsabilités et une formation des agriculteurs est nécessaire pour améliorer la situation présente non durable